Hollow carbon nanospheres/silicon/alumina core-shell film as an anode for lithium-ion batteries

Hollow carbon nanospheres/silicon/alumina (CNS/Si/Al₂O₃) core-shell films obtained by the deposition of Si and Al₂O₃ on hollow CNS interconnected films are used as the anode materials for lithium-ion batteries. The hollow CNS film acts as a three dimensional conductive substrate and provides void space for silicon volume expansion during electrochemical cycling. The Al₂O₃ thin layer is beneficial to the reduction of solid-electrolyte interphase (SEI) formation. Moreover, as-designed structure holds the robust surface-to-surface contact between Si and CNSs, which facilitates the fast electron transport. As a consequence, the electrode exhibits high specific capacity and remarkable capacity retention simultaneously: 1560 mA h g^-1 after 100 cycles at a current density of 1 A g^-1 with the capacity retention of 85% and an average decay rate of 0.16% per cycle. The superior battery properties are further confirmed by cyclic voltammetry (CV) and impedance measurement.